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M874 Armored Troop Transport
The M874 Armored Troop Transport (ATT), nicknamed Pangolin, is a variant of the standard M831 Troop Transport which is suited for operations in areas of heavy combat. As its name suggests, the Pangolin features armored gullwing doors over the driver and passenger sides of the vehicle and split armored doors on the passenger module in the back, which has also been enlarged to make up for space lost in enclosing it. Being used in combat heavy environments it also features a M43 Remote Weapon Station (RWS) mounted ahead of the troop module and behind the crew compartment. Origins Development History Operational History Role and Usage Design Specifications Mobility 'Chassis' Despite the radical differences between the M831 and M874, they do retain a common chassis design, that of the M12 Warthog. The M874 Pangolin features a monocoque chassis which means that its chassis and body are a single unit which itself is composed of a titanium frame along with carbon nanotubes which surround the the titanium, providing further structual support and rigidity to the frame. The primary layer of ballistic protection comes from the usage of titanium armor and ballistic polycarbonates which make up the outer skin and immediate surface of the vehicle, allowing it to sustain shots from a variety of small arms and even some heavier weapons such as machine guns with exceptional ability. Behind this outer layer is a network of carbon nanotubes and titanium structural supports which further bolster the toughness of the vehicle. The carbon nanotube supported titanium frame continues throughout the vehicle, through the frame of the troop bay and crew area, all the way down into the engine bay. The engine bay and rear seating area in particular feature large amounts of extra cross-bracing to prevent the vehicles body getting warped in the event of a crash or other impacts such as falling. This also serves to encase the crew compartment in a well protected tub, which ensures their safety either in a roll, crash or fall. Both the crew compartment and seating area in the back, feature blast reducing seats which prevents or at least decreases the jarring done to the troops inside in the event of en explosion under the vehicle. The most striking difference of the Pangolin from its cousins, and its namesake no less, is the addition of eight armored doors to both the troop area and crew compartment. The doors in the crew compartment are of a single piece, gullwing design and open upwards, away from the vehicle, this design was chosen as split doors which opened left and right would block the view of the crew member dismounting the vehicle. As they are to protect the crew, the two doors of the troop bay are composed of several different layers, to achieve the most protection for the lowest amount of weight. *The primary and outermost layer of the doors is one of Titanium armor, which allows the vehicle to sustain ample amounts of damage from both plasma and ballistic weapons, the latter being further hampered by the angling of the door, making it more likely to ricochet rounds. *After an airpocket is the secondary layer of the armor which is a layer of Titanium carbide, these ceramics are specifically implemented to absorb heat which gives the vehicle substantial protection, when paired with the titanium, against incendiary weapons as well as making it tougher against plasma weapons. *After another gap is the main Titanium frame upon which the armor is mounted which provides structural support for the door and armor *Both beneath the frame, and even within some spaces in it, is a layer of Hydrostatic gel, which maintains the temperature on the inside of the vehicle and prevents the crew inside from becoming too hot or too cold. But under sufficient temperature shock there is a chance for the gel to fail. *In the event of Gel layer failure there is a final layer of Aluminum 7075 alloy armor between the potential ballistic or environmental hazard and the crew inside. *The final piece of the armor is a simple Kevlar spall liner to prevent or reduce shrapneling in the event of a penetration by a weapon. All doors on the Pangolin are composed in this way to ensure the crew and mounted troops are as protected as they could be in a combat or in extreme heat or cold. The complement of 8 marines or 5 Spartans are to be seated in the rear bed of the Pangolin which, like the M831, features a large padded bench mounted in the center, capable of seating 3 Marines on each of the side benches and two at the end of the bench. Spartans cab be seated in a similar manner, but with only 2 per side bench and one at the end due to their greater weight and size taking up more space. The troop bay is covered on all sides by three sets of split, vertical opening doors which open in two sections, one upwards and one downwards. The advantage of this layout is that it allows the embarked troops to open the upper half and fight from within the vehicle with ample cover for their bodies, and it provides an unobstructed view of the dismounting area when both are opened. The doors are opened by a simple two piece latch at the seam between the doors, one for the upper half and one for the lower, conversely there is also a rapid opening method which requires pressing and holding down either the upper or lower latch as opposed to pressing them and letting go to disengage the locks. The final part of the rear doors is the viewports, there are two viewports on each side of the Pangolin wand its rear, which are composed of Aluminium oxynitride which is mounted in a carbon nantotube supported frame, allowing it impressive bullet resistance. A similar glass and frame is present on the driver and passenger doors. The viewports facilitate the usage of two firing ports on each set of doors of the troop bay, these firing ports allow the usage of MA5/37 assault rifles, BR55/85 battle rifles and other small arms, allowing the crew to fight from the inside of the vehicle. 'Drivetrain' 'Powerplant' The M874 Pangolin is powered by a Kristoff & Clifford 12.0 Liter Hydrogen Powered Engine-44627, abbreviated to K&C HPE-44627 or just HPE-44627. The HPE-44627 is a derivation of the standard Hydrogen ICE found in the normal M12 and M831 Warthogs but retains an 83% parts commonality. As the Pangolin was heavier than either the Warthog or Troop Hog, the powerplant also needed to be improved to allow the vehicle to maintain its battlefield mobility and off-road capability. The result of this was the HPE-44627 which features a greater power output and more torque while maintaining a favorable fuel efficiency even at high speed. The most noticeable improvements of the HPE-44627 are undoubtedly its Twin-charging, system which combines a centrifugal supercharger with a variable-geometry turbocharger to allow air to be forced into the engine and thereby increase its power and torque, the reason for the twin-charging is that the use of a supercharger and turbocharger means that air is being forced into the engine at all times. The supercharger used is a variant of the AMG Transport Dynamics CSC-226 'Tusk' High Performance Supercharger which is an optional extra on the civilian 'Hog'. The difference between the standard 'Tusk' and that used on the Pangolin is the robustness and reliability of the supercharger, whereas the civilian variant is slated for maintenance every 27,000 miles, the model used on the Pangolin is able to go an extra 23,000 miles for a total of 50,000 miles through the use of more expensive and far more capable air filters. Further reliability is provided by the use of anti-corrosive coatings and a redesigned impeller which is capable of operating even with large amounts of pollutants on it. On the performance side the supercharger increases standard power output by 41% and low speed torque by 21 % which allows the Pangolin to both accelerate better and remain more mobile at low speeds such as those required in tight city streets. These performance figures are possible not solely due to the supercharger but also the crankshaft which has been reinforced and allows the engines to operate at a higher RPM, increasing the speed of the impeller in the supercharger. The turbocharger used was developed specially for the Pangolin by AMG Transport Dynamics and is known as the VGTC-0276 'Claw' Variable Geometry Turbocharger. While the 'Tusk' supercharger was modified from a civilian to military requirement, the 'Claw' turbocharged was developed with military use at the forefront, this is evidenced by the intensive stress testing the turbos are put through, being made to run while being sprayed with water, mud, sand and other environment samples until they fail. As a result of this testing, and the decidedly less obstructive exhaust fumes when compared to fossil fuels, the 'Claw' is able to go between 43 and 51,000 miles without being cleaned out, depending on the terrain it is used on. Performance wise the 'Claw' turbocharger delivers a decent 32% power increase and a torque increase of 41%, this being an intentional design by AMG to allow the turbo to last far longer by operating at a lower boost pressure and generate the torque which the supercharger can't due to the crankshaft limitation. The combined use of the 'Tusk' supercharger and 'Claw' turbocharger allow the Pangolin to output an impressive 370 brake horsepower (bhp) for a power to weight ratio of 43.66 hp/ton and torque of 1,392 N-m (1,027 ft-lbs) at 3,400rpm with a redline of 6,100rpm which allows it to reach an on-road top speed of 125 km/h (78mph) and an off-road top speed of 115 km/h (71mph). The latter being maintainable due to the impressive off-road ability of the M874 and by extension the M12 series. However, due to the large armored doors mounted on the tall troop bay and the installation of the remote weapons station in front of it, the top speed is rarely ever used anywhere except open terrain or roads, with the vehicle often operating at lower speeds in practice to reduce the risk of rolling it. In the event of damage to the engine, the Pangolin features a variety of safety systems to prevent a catastrophic detonation of the engine as well as diminishing incoming damage as best it can. Engine maintenance is conducted by opening of the horseshoe shaped hood, which allows access to the air filters, cylinder heads, valves and main engine block. For in-field maintenance to the super or turbocharger, the vehicle needs to be lifted up which distends the wheels from the wheel arches and allows for access to the supercharger or turbo, a simpler method is the removal of the titanium fenders and inner wheel arch but this is not always possible in combat environments as it takes an extended amount of time to place them back. Refueling of the engine takes place from a filler port below the seating area for the passenger, the HPE-44627 is capable of taking all forms of water including mineral, brackish or even swamp water thanks to a Graf/Hauptman solar/saline actuator, which is capable of converting up to twelve liters of water into hydrogen on the fly. Detritus from the process is stored on board and disposed of by a flushing system which is activated from the center console in the crew compartment. This allows the Pangolin to travel 870 kilometers (540.6 miles) before it needs to be refueled, a range that can be easily extended by the addition of jerrycans or external fuel tanks to over 1000km. Armaments Unlike the M831 which it is derived from, the M874 Pangolin contains a mounting point for the M43 Remote Weapons Station (RWS). The M43 is a black sheep amongst vehicle mounted turrets in the UNSC as it is not crew serviced but rather is controlled by a screen which folds out from behind the passenger, along with this an arm with a control stick extend out from the dashboard. The turret is mounted above and behind the crew compartment, above the main vehicle spotlight and is capable of full 360-degree rotation and is capable of -20 to +50 degrees in depression and elevation respectively. The mount is fully gyro-stabilized and can mount weapons of up to 20mm on board. The sight package located on the left side of the turret contains a high definition day-night camera with a thermal camera mounted next to it and an eye-safe laser rangefinder. 'Primary Weapons' While most commonly fielded with the M247T 7.62mm Machine Gun, the M43 is capable of attaching a variety of other weapons and launchers including: *M41 'Vulcan' 12.7mm Heavy Machine Gun x 1 *M46 'Vulcan' 12.7mm Heavy Machine Gun x 1 *M460 40mm Automatic Grenade Launcher x 1 *M638 20mm Autocannon x 1 Both the M41 and M46 'Vulcan' Heavy Machine Guns are fairly common mounts as the increased stopping power of the 12.7mm rounds and the higher fire rate are far more effective against enemy infantry and low flying aircraft. However, to manage either of them, the weight of the turret is increased substantially, both due to the triple barrel design and the large, heavy ammo boxes which include 250-round box magazines, 400-round drum magazines or 500 round box-magazines. This results in the turret being heavier and having a slightly lower rotation speed which, combined with the longer barrels, make the weapons ability protect around the vehicle more difficult. Both are often fielded with the Compact Launch System (CLS) to allow the vehicle greater versatility in engaging targets. The M43 is also capable of mounting the M460 40mm Automatic Grenade Launcher which is usually fielded with units operating in vehicle heavy environments or areas with dug in troops. The M460 utilizes a 40 round box magazine and includes several types of ammo including High Explosive (HE), Proximity Fuse (HE-VT), and High Explosive Dual Purpose (HEDP) which have a secondary EMP mode, the launcher is most often fielded with the latter. When the system is operating in a riot or non-lethal force situation, the aforementioned rounds are exchanged for smoke, tear gas and even rubber bullets to neutralize threats or pacify mobs. The least used and most powerful of the M43's options is an M638 20mm Autocannon, derived from the one used on the Falcon. The M638 despite its power, accuracy and potency as a weapon seldom seen used on Pangolin's for several reasons. The weight of such a large gun, so high up on the vehicle makes the chances to rolling the vehicle far higher, the size of the gun also makes it even easier to hit and disable, the larger rounds making the potential ammo cook-off from the 100 or 200-round box magazine more damaging in the event it happens. The recoil of the gun also reduces the life of not just the stabilizers but also the turret itself as constant firing can weaken the mount or even warp the structure its mounted to. However the greatest reason is the abysmal rotation speed and sub-par depression which make the M638 a seldom used weapon, however there have been cases of Pangolins with 20mm guns being used as stationary pillboxes. 'Secondary Weapons' Aside from these there can also be accessory weapons alongside the main weapon, this in most configurations is the LAU-72 Compact Launch System (CLS) which contains four, 60mm ASGM-4 missiles. The ASGM-4 are high explosive missiles which travel at relatively high speed and are most often used to engage low flying craft such as Banshees or other craft, they are also used to target light vehicles such as Ghosts, Revenant's or even other Warthogs. The targeting software used in the missiles allow it to be a fire and forget missile and can attack on specific attack paths including ground skimming and top attack, the latter being exceptionally useful against Wraiths due to their large open gun mounts.While these missiles are non-reloadable in combat, they can be rearmed at a garage or base. The LAU-72 can be used alongside the aforementioned HMGs however caution is advised in using it alongside the M460 AGL due to the chance of the grenade launcher taking fire and possibly exploding which would cause a chain reaction and detonate the missiles or vice versa which would destroy the whole vehicle. Conversely if a non-lethal response is needed or if the vehicle needs to disengage or cover its deployment, a cell of eight smoke grenade tubes can be mounted in place of an accessory weapon but could also be loaded with tear gas to disperse crowds. Further non-lethal weapons such as M460 AGLs with rubber bullets or even high power hoses can be employed in the RWS when operating in riot operations. 'Sensors and Targeting Systems' The sensor package of the M43 Remote Weapons Station (RWS) prior to the outbreak of the Human-Covenant War was decidedly smaller and more compact, so as to keep the profile of the turret low and the optics safe, close to the gun-shield. However, when the M43 was upgraded to respond to the Covenant threat, its sensors and optics saw a massive improvement to be able to respond to the new threat and style of combat. As the turret itself was up-gunned to be compatible with a wider variety of munitions, so too was the targeting software. The new 'Owl' Fire Control System (FCS) allowed for acquisition of targets, ballistic correction and engagement out to ranges of 2 kilometers for weapons from 7.62mm to 20mm, each with their own presets programmed into the FCS. To further improve long range accuracy, the firing solutions for the equipped weapon are updated as a target is being engaged, allowing the vehicle to combat moving targets while stationary or on the move itself. To improve the situational awareness of the gunner, the FCS is also fed data from six, wide angle sensors, three on each side of the turret, which are able to target and obtain solutions on targets which are not in the current line of sight. Along with the FCS, the three main camera sights through which the gunner views the battlefield were also upgraded. The previous goals of compactness were abandoned during the upgrade and saw the replacement of the compact cameras with larger high definition cameras to allow for engagement at longer range. The first of these three camera sights is the primary viewing camera which is a M221 Day-Night FHD Camera System, otherwise nicknamed the 'Cyclops' due to how much larger it is than the previous cameras. The M221 features a wide FOV lens which along with the FCS can make engaging or responding to several targets easier, the lens can manage a a variety of zoom levels from a x1-x14 for use at long range. While in some cases the ability to make out targets at such ranges could be hampered, this does not occur in the M221 which utilizes a FHD 1440p x 1080p display, giving the gunner a clear sight during combat either in darkness or in daylight. The second camera sight, which is smaller than the M221 but is still rather large, is the M711 Multi-Wavelength Gun Sight. This camera allows the gunner to engage targets in complete darkness or similar situations of visual obstruction such as heavy snow, rain or in dust storms. The camera itself is rater at 1440p x 1080p and is capable of covering a wide range of the electromagnetic spectrum, giving a wide range of view modes to better adapt to situations. As with the M221, the M711 also has a connection to the FCS and has its own presets, reticle and display parameters for firing the turret is adverse conditions. In regular combat the M711 behaves as a thermal sight capable of picking up enemy heat signatures and engaging them out to the same 2 kilometers thanks to the FCS. The third sight is not especially large, has a fairly low field of view FOC and resolution of only 1080p x 720p, however, the M393 Back-up Gun Sight is nonetheless a vital part of the optical package of the M43 as its small size and capability to fight at night and day ensure that the vehicle is able to respond to fire even if its main optical systems are disabled. On the control and targeting aspect of the M43, viewing through the optics is provided by a 1440p x 1080p, 144hz screen which folds out from behind the passengers seat. The display is fed by the trio of cameras on the turret and is held in front of the passengers by a stabilized arm which allows its easy use, even over rough terrain. Furthermore the screen is linked to a trio of sensors on the right and left side of the turret which cover a cumulative 360 degrees which allows targets outside the line of sight to be tracked and identified to make engaging them easier. Actual movement, aiming and firing of the turret is managed via a fold out arm which is beneath the seat of the passenger and at its end, has a controller like device with two analog stick, one for elevation and the other for rotation, and two triggers, one for firing the main gun and another for switching between zoom levels either by stages or gradient depending on the setting. When not in use, the arm the controller is attached to collapses into a metal cover beneath the seat so as to reduce the risk of it injuring the passenger in a crash. 'M48 Remote Weapons Station' As the M43 was developed to fight the Insurrection it sported a relatively weak gun, when compared to those of the M12 line, therefore in order to mount HMGs a series of field modification kits were introduced to allow mounting of weapons of up to 20mm by the use of far improved stabilizers and targeting software. This however had the aforementioned drawbacks as the extra weight decreased the rotation speed, hampering its effectiveness of the turret to support infantry. Furthermore the lack of an adequately sized gun shield to make space for the camera, sensors and missile pod, meant that the gun is also far less protected and prone to getting disabled, making it fall out of favor compared to better protected crew serviced guns. As a result of these issues, Misriah Armory has been working on developing a new M48 Remote Weapons Station which is far more robust than the older M43 in that it is made with stonger parts and features stabilization for weapons up to and including 14.5mm. It mounts a new gun shield which is 30mm thick and is made of Titanium-A3 derived armor to better handle impacts from plasma weapons, add on ceramic plates can also be fitted to further its protection. The development of more compact and higher resolution day-night optics also means that more space can be taken up by the gun shield and ammo boxes, meaning further protection and a greater amount of ammo carried. Despite the attempts to make the turret more survivable Misriah has also added in an option to 'eject' the turret should it be disabled or if the ammo risks cooking off and damaging the vehicle in which case the mounting locks are disengaged and the mounting arm is extended outwards, pushing the turret up and out of its mounting so it may roll off from the vehicle. Variants Category:UNSC Vehicles